Voltage regulators



June 23, 1959 J. GARsHELls 2,892,145

VOLTAGE: REGULATORS Filed June 7, 1956 2 Sheets-Sheet 1 ATTORNEYS June 23, 1959 l. J. GARSHELIS 2,892,145

VOLTAGE REGuLAToRs Filed June 7. 1956 2 sheets-sheet 2 ATTORNEYS Unite States arent M VOLTAGE REGULATORS Ivan J. Garshelis, Bronx, N.Y.

Application June 7, 1956, Serial No. 590,029

6 Claims. (Cl. 323-19) The present invention relates, in general to vacuum tube circuits in which the plate current is controlled by a magnetic iield and, in particular, to voltage regulator circuits utilizing a magnetically controlled vacuum tube.

An object of the present invention is the provision of a voltage regulator circuit utilizing a non-gaseous tube and which is capable of the same percentage regulation as a voltage regulator circuit utilizing a gas tube.

Another object is the provision of a voltage regulator vacuum tube circuit wherein the nominal or regulated voltage may be adjusted by means of variation in the strength of a magnetic field, and wherein the adjustability is practically unlimited in range and may -be in the order of hundreds to one.

Another object is the provision of a voltage regulator circuit which has no unstable region.

Another object is the provision of a voltage regulator circuit which has practically no limit to the current range in which it can operate.

Another object is the provision of a voltage regulator which has practically no limit as to the range of voltages that it can handle. i

Another object is the provision of a voltage regulator circuit which does not require higher than nominal starting voltage.

Another object is the provision of a voltage regulator circuit which is not subject to relaxation oscillation.

Another object is the provision of a voltage regulator circuit which provides a faster response than conventional voltage regulator circuits.

A further object is the provision of a voltage regulator circuit wherein the nominal voltage is unafected by tube life, ambient temperature, and ambient light conditions.

The above and other objects, featuresr and advantages of the present invention will be more fully understood from the following description considered in connection with the accompanying illustrative drawings. f

In the drawings 'which illustrate the best modes presently contemplated of carrying out the invention:

Fig. l illustrates a voltage regulator circuit pursuant to the present invention;

Fig. 2 is a plate current vs. plate voltage characteristic curve for a simple diode tube and for the tube in the voltage regulator circuit of Fig. 1;

Fig. 3 illustrates an additional embodiment of a voltage regulator circuit pursuant to the present invention;

Fig. 4 illustrates a further embodiment of a voltage regulator circuit pursuant to the present invention;

Fig. 5 illustrates plate current vs. plate voltage characteristic curves for the circuit illustrated in Figs. 3 and 4; and

Figs. 6 and 7 are curves illustrating variation in the strength of the magnetic field with variations in input voltage and load current, respectively, for the circuit of Fig. 4. l j

j Referring now to Figs.` 1 and 2 in detail, the voltage regulator circuit 10 comprises a `diode vacuum tube 12 having a plate or anode 14 and acathode 16. The elec- 2,892,145 Patented June 23, 1959 ICC trodes 14 and 16 are coaxial and concentric with the anode about the cathode. Provision is made for a permanent horse-shoe magnet 18 which provides a constant magnetic eld parallel to the axis of the tube 12. The input terminals for the circuit are indicated at 20 and 22, respectively. The terminal 20 is connected through a fixed resistor 24 to the anode 14, and the terminal 22 is connected to the cathode 16. The output terminals for the circuit are indicated at 26 and 28. The output terminal 26 is connected to the anode 14 and the output terminal 28 is connected to the cathode 16. A variable load resistance is indicated by the reference numeral 30 and is connected across the output terminals 26 and 28 in parallel with the tube 12. Consequently, it lwill be noted that the fixed resistor 24 is connected in series with the tube 12 and that the output load 30 is connected in parallel with the tube 12.

Fig. 2 illustrates a characteristic curve for a diode having essentially coaxial concentric electrodes, the plate current being plotted against the plate voltage. The reference numeral 32 indicates the :simple diode characteristic curve for the diode 12, when not subjected to the axial magnetic field, and it will be noted that this curve is essentially a straight line. The reference numeral 34 shows the resultant curve 34 where the diode 12 is subjected to an axial magnetic field, as by the magnet 18, which converts the tube into a low dynamic impedance device, a small change in plate voltage producing a lange change in plate current.

As is well known, the equivalent resistance of the tube 12 is the plate voltage divided by the plate current at the particular plate voltage. Without the magnetic field, the equivalent resistance of tube 12 does not vary appreciably throughout the useful range of the characteristic curve 32 since the curve is essentially a straight line. However, with the introduction of the magnetic field, resulting from the presence of the magnet 18, there is a radical change in the characteristic curve of the tube 12, as will be apparent by a comparison of curve 34 and curve 32. The axial magnetic eld prevents electrons emitted by the cathode from reaching the plate until a certain critical voltage is applied to the plate. The critical voltage is indicated at VC in Fig. 2. When this critical voltage is applied to the plate, the plate current doesnt change gradually With a change in plate voltage, as in curve 32, but the plate current changes very radically with a change in plate voltage as indicated by the portion of curve 34 between the points denoted thereon by reference numerals 36 and 38. It Will be noted that the curve 34 between said points approaches a vertical line being sloped toward verticality. Over the portion of curve 34 between `said points there is a radical change in the resistance of the tube 12. Further, it will be noted that this radical change in resistance occurs with a relatively small change in the plate voltage, as will be apparent from the sharp slope of curve 34 which occurs between the two relatively close plate voltage points indicated by V1 and V2 which, of course, indicate a relatively small change in plate voltage. With this small change in voltage there is a radical change in both the equivalent resistance of the tube and in the plate current thereof. The small increase in plate voltage from V1 toV V2 cau-ses a large increase in plate current and the small decrease in plate voltage from V2 to V1 causes a large drop in plate current.

With the tube 12 having a characteristic curve as indicated by the curve 34 due to the axial magnetic field supplied by the magnet 18, and operating in the portion thereof between points 36 and 38, if there is a large increase in input voltage applied across the input terminals 20 and 22, only a very small part of lthe increased voltage `will .appear across the load resistance 30 or between the output terminals 26 and 28. As will be apparent from curve 34 an increase in the plate voltage 'of the tube 12.

along the portion of the curve between the points 36 and 38 will cause a much larger increase in 4the plate current with a resultant great decrease in the resistance of the tube 12. Due to the large decrease in the resistance of tube 12, which is in series lwith the fixed resistor 24, most of the voltage drop resulting from the increased plate current will appear across resistor 24 and practically none will develop across the tube which is in parallel with the load 30. Consequently, the major portion of the increase in the input voltage is developed across the fixed resistor 24 and only a very small portion of the increase in the input lvoltage is developed across the tube 12 which is in series with the resistor 24. The large decrease in the tube resistance is caused by a comparatively small change in plate voltage, for example, by the voltage change between the voltage values V1 and V2 and this is accompanied by the very same small change in the output voltage developed across the load 30, since the tube 12 and the load 30 are in parallel.

In the event that the input voltage applied to the input terminals and 22 should decrease, the reverse of the foregoing operation occurs. With a decrease in the input voltage, the tube resistance increases greatly, as will be apparent from the curve 34, so that the major portion of the decrease in the applied voltage occurs as a decrease in the voltage across the resistor 24. This is due to the fact that the plate current drops radically and very little of the decrease in input voltage appears across the tube 12 due to the greatly increased resistance thereof. Since the output load is in parallel with the tube 12 very little of the decrease in the input voltage appears across the output load.

In the event that the load resistance is decreased greatly, the tube resistance, in parallel therewith, increases greatly causing only a small net increase in current through the fixed resistor 24 accompanied by only a small additional voltage drop in said resistor 24 and thus lowering the output voltage only the small amount necessary to cause the change in tube resistance.

In view of the foregoing, it will be apparent that the tube 12, subjected to the axial magnetic field provided by the magnet iti, operates as a low dynamic impedance device, the equivalent variational or plate resistance thereof being much smaller than is the case where the magnetic eld is not utilized. I have found that the voltage regulator circuit 10 is capable of as precise regulation as conventional voltage regulator tube circuits and, in addition, has the various advantages which are set forth in the objects of the present invention; and which also appear in connection with the circuits of Figs. 3 and 4.

Referring now to Fig. 3 in detail, there is shown a voltage regulator circuit 4G which provides for closer voltage regulation than the previously described voltage regulator circuit 1t). The regulator circuit 4i) uses a similar diode tube 12, as in the prior regulator circuit, wherein the anode 14 and the cathode 16 are concentrically coaxial. The input terminals are indicated at 2t) and 22, and the output terminals are indicated at 26 and 28, and provision is also made for the fixed resistor 24, at the input terminal 2t), and for the variable resistor 30, representative of the variable load resistance which is connected across the output terminals 26 and 28.

Pursuant to the present embodiment, provision is also made for a magnetic field which is parallel to the axis In this connection, provision is made for the soft iron core 42, in the shape of the permanent magnet 18. The core 42 has embodied therein a permanent bar magnet 44. Consequently, the resultant manetic field is polarized, as indicated by the polarities at the confronting ends of the core. In addition, provision is made for a solenoid winding 46 which is wound about the core 42 so as to provide an electromagnetic field of opposite polarity to the magnetic held provided by the permanent magnet 44 as will be apparent from the indicated polarities. One end of the solenoid is connected to the anode 14 and the other end thereof is connected between the fixed resistor 4 and the output terminal 26. Consequently, it will be noted that the output load 30 is in parallel with the tube 12 and the solenoid 46. In this connection, it will be understood that the resistance of the solenoid Winding 46 is quite low so that there is no appreciable voltage drop across the solenoid.

In view of the foregoing, it will be apparent that a main or basic magnetic field parallel to the axis of the tube 12 is provided by the permanent magnet 44 and that the electromagnetic field resulting from current flow through the solenoid winding 46 is in opposition to the main magnetic field so as to provide a resultant or net field the magnitude of which will vary with the magnitude of the electromagnetic field. The basic voltage rating of the voltage regulator circuit 4() is established by the net magnetic field with no load connected across the output terminal. For example, and not by way of limitation, with a magnetic field of l0() gauss established by the permanent magnet 44 and with a current input of 25 milliamperes applied to the input terminals 2Q and 22, and with no load across the output terminals 26 and 28, the net magnetic field would be approximately gauss and the output would be approximately 200 volts.

The net magnetic field resulting from the interaction of the magnetic field of the permanent magnet 44 and theelectromagnetic field of the solenoid coil 46 controls the current flow through the tube 12. Without a magnetic field parallel to the axis of the tube 12, as described, an increase in input voltage would result in an increase of the voltage drop across both the fixed resistor 24 and the tube 12, as well as an increase in the voltage drop across the load resistance. However, with the establishment of the net magnetic field by the interaction of the permanent magnetic field and the electromagnetic field, the increased input voltage causes the current through the tube 12 to increase and this in turn increases the electromagnetic field generated by the solenoid winding 46 which, in turn, reduces the net field since it is in opposition to the permanent magnetic field. The reduction of the net magnetic field permits more current to flow through the tube 12 thereby increasing the voltage drop across the fixed resistor without however increasing the voltage across the load resistance. In other words, the tube 12, subjected to the axial magnetic field, acts as a variable resistance so that with increased input voltage the resistance offered by the tube 12 decreases to increase the current through the tube and therefore preventing the increase of current through the load resistance, which is in parallel with the tube. Consequently, since all of of the increased current flows through the resistor 24, all of the additional or increased voltage applied to the input terminals is developed across the fixed resistor and not across the load resistance 30. Assuming now that the voltage at the input to the regula tor tube circuit 40 decreases, the opposite effect takes place. The tube now acts as a higher or increased resistance so that there results a `decrease in current flow through the tube and through the resistor 24 thereby lowering the voltage drop across the resistor 24 so that the voltage across the load is essentially unchanged.

Assuming now that the input voltage applied to the voltage regulator tube circuit 40` remains constant and that the resistance of the load 30 increases, the resistance of the tube decreases so that more current fiows through the tube and less through the load. If however, the load resistance decreases the resistance of the tube increases and more current flows through the load and less current ows through the tube.

It will be noted in each of the foregoing conditions, since the tube 12 and the load resistance 30 are in parallel and since the total current through the circuit flowsthrough the fixed resistor 24, any change inthe input voltage or in the output resistance or load results in a change of current flow in the circuit which is compensated for or accommodated by the tube 12 so that the output voltage developed across the load resistance remains constant.

Referring now to Fig. 4 in detail, there is shown another embodiment of the present invention, similar reference numerals being utilized to indicate the same components as in Figs. 1 and 3. It will be noted that the voltage regulator circuit 48 is provided with the permanent magnet 44, the core 42, and the solenoid 46 in series with the tube v12, to provide an electromagnetic field in opposition to the magnetic field provided by the magnet 44, all as previously described. In addition, provision is made for an additional solenoid 50, provided on the core 42. The solenoid 50 is connected in shunt with the tube 12, being connected between the input terminals 20 and 22 in series with a fixed resistor 52, the latter being optional so that it can be omitted. It will be noted that the electromagnetic field provided by current flow through the solenoid 50` is in the same direction as the magnetic field provided by the permanent magnet 44 so as to aid the field of the latter. Consequently, it will be apparent that the electromagnetic field provided by the solenoid 46 opposes the magnetic field provided by magnet 44 and that the electromagnetic field provided by solenoid 50 aids the magnetic field of the permanent magnet 44. It will also be noted that provision is made for a load resistance 54 which is connected in series with tube 12, being connected in series with the cathode 16 as shown. The output terminals 26 and 28 are connected across the load resistor 54.

In the present embodiment, since the load resistance 54 is in series with the tube 12, the current flowing through the load also flows through the tube. Furthermore, it will be noted that the current flow through the load resistance and the tube 12 also flows through the solenoid 46 which is in series with the tube 12. As previously indicated, the magnetic field provided by the solenoid 46 is in opposition to the main magnetic field provided by the permanent magnet 44. Therefore, it will be apparent that the electromagnetic field provided by the solenoid 46 is in opposition to the main magnetic field and in addition is proportional to the load current. The solenoid 50 is in shunt with the tube 16 and the load resistance 54 and, as previously indicated, provides an electromagnetic field which aids the magnetic field provided by the permanent magnet 44. The shunt solenoid 50 being connected across the input terminals 20-22, the magnetic field thereof is proportional to the input voltage and, as indicated, aids the main magnetic field.

With a constant input voltage across the terminals 20- 22, the eurent through the load resistance 54 will be equal to the current through the tube 12, and the voltage output across the output terminals 26-28 will be equal to the input voltage minus the voltage across the tube 12. If now the load current increases, the output voltage across the output terminals must still be equal to the input voltage across the input terminals 20-22 less the voltage across the tube 12. Therefore, to provide a constant voltage across the load 54, even though the load current has increased, it Iwill be apparent that the voltage across the tube 12 must be equal to the previous condition with no increase in the load current and with a constant input voltage. In other words the increased current flow through the tube must not cause an increase in the voltage drop across the tube.

The increased current through the load, and the consequent increased current through the tube 12 in series with the load, also causes increased current fiow through the series solenoid 46 so as to increase the strength of the electromagnetic field which lis in opposition to the main magnetic field and, consequently, to reduce the net magnetic field. Therefore, the increased current flow through the load and the tube is compensated for by the increase in the opposing electromagnetic field and the consequent reduction in the strength of the net magnetic field. As previously indicated, the tube` subjected to the axial magnetic field acts as a variable resistance or Voltage sensitive device, so that the resistance of the tube decreases withthe reduction in the net magnetic field and with the increased current. Consequently, the voltage drop across the tube 12 does not change and the output voltage across the load resistance 54 remains constant.

Assuming now that the load resistance is constant but that the voltage input increases so as to tend to drive higher current through both the tube 12 and the load resistance 54, the voltage drop across the tube 12 must increase so as to prevent an increase in the voltage drop across the load resistance 54. This is accomplished by an increase in the net magnetic eld due to the increased current flow through the shunt solenoid 50, which, as previously indicated, provides an electromagnetic field which is proportional to the input voltage and which aids the main magnetic eld so as to increase the net magnetic field. This results in an `increase in the resistance of tube 12 so that the voltage drop across the tube increases to compensate for the increased input voltage.

Figs. 5, 6 and 7 illustrate the operation of the voltage regulator circuit 48. Fig. 5 illustrates the tube characteristic curve for the tube 12 in the voltage regulator circuit 48 with the input voltage remaining constant. As previously indicated, the output voltage will be equal to the input voltage minus the voltage developed across the tube 12. The three curves B1, B2 and B3 indicate'the net field in gauss, B1 being the maximum or strongest net field, B2 being an intermediate value, and B3 being the weakest net field. It will be noted that at a specific plate voltage value, here designated as VT, for example 200 volts, the plate current being indicated in milli-v amperes, at the plate current value indicated by I1 the net field is at its maximum. As the plate current value increases to I2, which is an intermediate value, and then to I3, which is a maximum Value, the net magnetic field decreases from B1, for the stated plate voltage Value VT, to the net field indicated by B2 for plate current value I2, to the net field indicated lby B3 for plate current value I3. Consequently, it will be apparent that as the `intensity of the net axial magnetic field of tube 12 decreases from a maximum to a minimum value, as the plate current value increases from a minimum to a maximum value, the voltage across the tube, as indicated by VT remains constant. Since the tube is in series with the load resistance 54, it will be apparent that the voltage developed across the load resistance will remain constant over the load current range Il-Iz-Ia.

Fig. 6 is a graph showing the relationship between the magnitude of the net magnetic field and the input volt-` age. It will be noted that with an increase in the input voltage the strength of the net magnetic field increases above the value of the main magnetic field, the latter, as previously indicated, being determined by the permanent magnet 44. Since the shunt solenoid 50 is connected across the input terminals 20'-22 in the voltage regulator circuit 48 and, since the shunt field `aids the main magnetic field, the increase in input voltage results in an increase in the net magnetic field.

Fig. 7 is a graph illustrating the relationship between the magnetic eld in gauss and the load current. As here shown, the load current is va minimum at I1, a maximum at I3, and an intermediate value Iat I2. The magnetic field is a maximum at B which represents the value of the main magnetic field as determined by the permanent magnet 44, B1, B2 and B3 being successively decreasing values. It will be noted therefore, from this figure, that as the value of the load current increases the net magnetic field decreases due to the fact that the load current flows through the series solenoid 46 which provides an electromagnetic field in opposition to the main magnetic field.

While the core 42 has been indicated as being made of soft iron, any other suitable core material having high permeability over a wide range of linx density, high saturation flux density, low hysteresis and low eddy current losses and low remanence may be used in lieu of soft iron.

From the foregoing, it will be apparent that in all three of the described voltage regulator circuits, a concentric coaxial diode tube is utilized and it is transformed from` its essentially straight line operating characteristic to a highly sensitive voltage device by means of an axial magnetic field. In the more precise series regulator circuit of Fig. 4 and shunt regulator circuit of Fig. 3, the

inexact verticality of the voltage-current curve 34 of Fig. 2 is` corrected by adding to or subtracting from a fixed magnetic field according to the current requirements of the load and the voltage input from the source. This is achieved by the use of the solenoids. All three circuits provide for the advantages previously set forth in the objects of the present invention.

While I have shown and described the preferred embodiments of my invention, it will be understood that various changes may be made in the idea or principles of the invention within the scope of the appended claims.

Having thus described my invention, what I claim and desire to secure by Letters Patent, is:

1. A voltage regulator circuit having a diode tube, input and output circuit means, and means to subject said tube to a magnetic field operable to alter the normal straight line plate current-plate voltage characteristic curve of the tube by increasing the slope of a substantial portion of said curve toward verticality, whereby to convert said tube into a voltage sensitive device when operated along said sloped portion ot its altered characteristic curve, the electrodes of said tube being coaxial and concentric, and said magnetic field means providing an axial magnetic field for said tube, said magnetic field means providing a fixed magnetic field and a variable magnetic field which interacts with said fixed field and which is variable in response to changes in voltage at said output circuit, to regulate the voltage thereof.

2. A voltage regulator circuit having a diode tube, and means to subject said tube to a magnetic field operable to alter the normal straight line plate currenbplate voltage characteristic curve of the tube by increasing the slope of a substantial portion of said curve toward verticality, whereby to convert said tube into a voltage sensitive device when operated along said sloped portion of its altered characteristic curve, the electrodes of said tube being coaxial and concentric, and said magnetic field means providing an axial magnetic field for said tube, said magnetic field means providing a fixed magnetic field and a variable magnetic field which interacts with said fixed field and which is variable in response to current fiow in said circuit.

3. A voltage regulator circuit having a diode tube, and means to subject said tube to a magnetic field operable to alter the normal straight line plate current-plate voltage characteristic curve of the tube by increasing the slope of a substantial portion of said curve toward verticality, whereby to convert said tube into a voltage sensitive device when operated along said sloped portion of its altered characteristic curve, the electrodes of said tube being coaxial and concentric, and said magnetic field means providing `an axial magnetic field for said tube, said magnetic field means providing a fixed magnetic field and a variable magnetic eld which interacts with said fixed field and which is variable in response t'o thc plate current fiow of said tube.

4. A voltage regulator circuit having a diode tube, and means to subject said tube to a magnetic field operable to alter the normal straight line plate current-plate voltage characteristic curve of the tube by increasing the slope of a substantial portion of said curve toward ver# ticality, whereby to convert said tube into a voltagesensitive device when operated along said sloped portion of its altered characteristic curve, the electrodes of said tube being coaxial and concentric, and said magneticfi'eld means providing an axial magnetic field for said tube, said magnetic field means providing a fixed magnetic field and a variable magnetic field which interacts with said fixed field and which is variable in response to the plate current flow of said tube, said magnetic fields being polarized in opposition to each other.

5. A voltage regulator circuit comprising a diode tube having coaxial concentric electrodes, means providing an axial magnetic field for said tube, input terminals across which said tube is connected, and output terminals across which to connect a load for regulation of the voltage thereof, said means comprising a magnetic core member provided with a permanent portion to provide a main magnetic field of predetermined polarity for said tube, and a solenoid winding on said core in series with said tube for the flow of plate current therethrough, said Winding having a polarity in opposition to said main magnetic field.

6. A voltage regulator circuit comprising a diode tube having coaxial concentric electrodes, means providing an axial magnetic field for said tube, input terminals across which said tube is connected, and output terminals across which to connect a load for regulation of the voltage thereof, said means comprising a magnetic core member provided with a permanent portion to provide a mainl magnetic field of predetermined polarity for said tube, and a solenoid winding on said core in series with said tube for the ow of plate current therethrough, said winding having a polarity in opposition to said main magnetic field, the output terminals of said circuit being connected across the series combination of said tube and said solenoid winding.

References Cited in the file of this patent UNITED STATES PATENTS 1,321,434 Hewitt Nov. 11, 1919 1,321,435 Hewitt Nov. l1, 1919 2,750,555 Kather et al. June 12, 1956 FOREIGN PATENTS 627,335 Germany Mar. 13, 1936 883,033 France Mar. 15, 1943 

